We carry out a systematic study of existing visual CAPTCHAs based on distorted characters that are augmented with anti-segmentation techniques. Applying a systematic evaluation methodology to 15 current CAPTCHA schemes from popular web sites, we find that 13 are vulnerable to automated attacks. Based on this evaluation, we identify a series of recommendations for CAPTCHA designers and attackers, and possible future directions for producing more reliable human/computer distinguishers.
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About me
Lead Google's anti-abuse research. Develop new ways to protect users and disrupt bad guys. Make Chrome safer and faster. Help keeping G+ and Gmail clean. Wear berets. Do magic tricks.